Telephonic transmitter.



- W. J. MARGHANT. ITELEPHONIVG TRANSMITTER. 'APILIOATION FILED AUG. 31, m1.

1,054,581. Patented Feb. 25, 1913] "IVIITNFSSEQ- m Mk A K CHANT, .a subject of' the King of Great the city of London, Englahd,.man ager, hare tions are collected or concentrated a die; phragm, to whichtypeoftransmitter my inf-v'e'ntion is restricted. The inventionjmay be I gitudinal section in the in or substantially in the focal plane of the To all whom it may concern phragms, and in so fixing the transmitter iiisiaian s me SPATENT @FFEQT} WILLIAM JOHN manciaan'r, or LOIt DON, ENGLAND.

Britain, residing, in London, England, and Whose post-ofii'ce -addressis Stolz Electra. phone Company Limited, 85 Fleet street, in

invented certain new and useful lmprove ments in Telephonic Transmitters, ofwhich the following-is aspecification, f The primary object of this invention is to increase the efficiency of audiphone apparatus of .Lthe kind comprising. telephonic transmitter and ."receiver in combination, but'it-will be obvious'tha't theinvention is applicable to telephonic transmitters; in general of the kind .in which the" s'ound vibi-a-.

described broadly as providing such transmitters with a mouthpiece or horn which is parabolic in section, such as have been previously proposed in association with telephonic transmitters unprovided with diaand horn withrespect to each other that the diaphragm of the transmitter-"occupies the focal plane of the horn eitherexactly or approximately, that part of the'paraboloid in rear of'the' focalf plane being-of course cut away. By means of such'an apparatus the sound Waves collected'in the horn are by reflection concentrated on the diaphragm, thereby obtaining increased loudness in the receiver associated with the transmitter -to which the horn is attached. f

Such an arrangement is illustratedi n lonaccompanying drawing, in whichr (1 represents the mouthpiece or h'orn which mayv be of metal or other suitable material and which has the shape of a paraboloid of revolution with thevendpart cut away, so that the rear edge of the horn terminates paraboloid constituting the horn, which in-' creases'in size from its rear'or inner end the front or outer end. v

' 12 represents the box ofjhe t ansmitter which may be of any suitable character. :1 mi j 0 represents the transmitter diaphme-z I 'rnnnrnomc TRANSMITTER.

I Specification of Iietters' Patent. 15341361113911 Ffil). 25, 1913. Application filed August 31,

1911. Serial 110,647,042.

locking over the mouthofthe horna one or more of a seriesof screens ofgauzeor'other suitable material for the purpose of gradu:

ating' the intensity of sound produced iii-the This apparatus is secured in-a suitable receiver. For convenience the box or casing d is made with-a compartment (Z at its rear end adapted to accommodate these screens which are made or material of varying thickness or mesh stretched over the rings j which are of a diameter adaptedto fit within the edge of the casing- (Z and ah'ut against the flange d When clamped in position by the clamping ringc.

Having thus described the nature of this invention and the best means I know of carrying the same-into practical efiect. I I cla1m:-

-A telephonic transmitter comprising a casing containing a horn or mouth-piece,-

having the shape of a paraboloid of revolution with the end part cut away so that the rear edge of the horn terminates approximately in the "focal plane of the paraboloid, the .said'horn increasing in size continuously frimi "the real" smaller end to the Ifront larger end, a daphragm'fixed approximately in the focal plane of the pa raboloid and com tiguous with the said rear edge of the horn, a series of removable sound graduating screens, and means carried by the casing for securing the screens one .atatime over the said large end of the horn.

In, testimony whereof I h n s signedniy name to this specification in the presence of two subscribing witnesses \VILLT'AM JOHN MARCHANT.

- Witnesses: James Slum-xsrauuc Siu'm, THIHUH Got iinor nx. 

